A wireless network may provide wireless coverage in a plurality of wireless coverage areas, such as cells and/or sectors. A mobile station may be served by the wireless network via a one or more of the wireless coverage areas. The one or more wireless coverage areas that are being used to serve the mobile station may be identified in an “active set” that is maintained for that mobile station. As the mobile station changes location, the wireless coverage areas in its active set may also change. Thus, wireless coverage areas may be added to or dropped from the mobile station's active set, for example, due to movement of the mobile station, changes in network load or radio frequency (RF) conditions, or other factors.
A mobile station may also receive a neighbor list from the wireless network. The neighbor list may identify one or more wireless coverage areas that are not in the mobile station's active set but may be neighbors to one or more of the wireless coverage areas in the active set. The mobile station may measure the signal strengths of pilot signals transmitted by the one or more wireless coverage areas in the neighbor list and report the measured signal strengths to the wireless network. When the mobile station reports a measured signal strength for a wireless coverage area in the neighbor list that is sufficiently high, then that wireless coverage area may be added to the mobile station's active set.
The wireless network may determine a neighbor list for a mobile station in various ways. In a conventional approach, each wireless coverage area may be associated with a respective list of predefined neighbors. The neighbor list for a mobile station may then be constructed as a composite of the respective lists of predefined neighbors for each of the wireless coverage areas in the mobile station's active set. Thus, when a wireless coverage area is added to a mobile station's active set, the predefined neighbors for that wireless coverage area may be added to the mobile station's neighbor list. Similarly, when a wireless coverage area is dropped from a mobile station's active set, a new neighbor list for the mobile station may be constructed based on the predefined neighbors of the one or more wireless coverage areas remaining in the mobile station's active set.